build docs only for tags

Author: krlmlr

tic.R

@@ -1,6 +1,6 @@
 add_package_checks()
 
-if (Sys.getenv("id_rsa") != "") {
+if (Sys.getenv("id_rsa") != "" && ci()$is_tag()) {
   # pkgdown documentation can be built optionally. Other example criteria:
   # - `inherits(ci(), "TravisCI")`: Only for Travis CI
   # - `ci()$is_tag()`: Only for tags, not for branches